Starting-switch for electric motors.



PATENTED JAN. 24, 1905.

' J. B. WIARD.

STARTING SWITCH FOR ELECTRIC MOTORS.

v APPLIGATION FILED MAY 27, 1904.

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UNITED STATES Patented January 24:, l 905.

PATENT OFFICE.

JOHN B. VVIARD, OF LYNN, h IASSAOI-IUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEIV YORK.

STARTING-SWITCH FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 780,547, date January 24:, 1905.

. Application filed May 27, 1904. Serial No. 210,049.

To all whom it may concern:

Be it known that I, JOHN B. TIARD, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Starting-Switches for Electric Motors, of which the following is a specification.

My invention relates to electrical switches, and has particular reference to centrifugal IO switches designed for use in alternating-current motors.

It is well known that in operating certain types of alternating-current motors it is desirable to provide different circuit connections for 5 starting and running. For this purpose some form of switching mechanism is usually employed by which the desired circuit changes may be made either manually or automatically.

The object of my invention is to provide a centrifugally-operated switch adapted for this purpose and possessing a n umber of novel and highly-advantageous features.

One feature consists in the compact arrangement of the switch, whereby it may be assem- 5 bled as a unit and mounted within a small space at the end of the revolving member.

A second feature consists in so arranging a switch that the movable contacts are entirely inclosed, thus enabling the switch to be used 3 in places in which there would otherwise be danger of fire, due to arcing.

Another feature consists in so arranging the resistance that absolutely no insulation is required in any part of the switch except between adjacent turns of the resistance.

Another feature consists in so arranging the centrifugal member and its retaining-spring that the tension of the spring is not appreciably increased when the centrifugal member 4 moves to close the switch-contacts, thereby enabling the centrifugal member to exert a firm pressure on the contacts.

Another feature consists in a novel form of terminals adapted to give excellent electrical contact with simple construction.

My invention will best be understood by reference to the accompanying drawings, in which- Figure 1 shows an end view of a centrifugal gether.

switch arranged in accordance with my inven- 5 tion, the outer cap and one section of the resistance being removed. Fig. 2 shows a side elevation in cross-section of the same mounted on the end of the rotating member of a motor, the cross-section of the switch being taken on 5 5 the line 1 1 of Fig. 1; and Fig. 3 shows diagrammatically the circuit connections.

Referring first to Figs. 1 and 2, A represents the rotating member of an alternating-current motor carrying the coils c0 and mounted on the shaft S, which is journaled in the bearing B. (0 represents the end plate by which laminations of the rotorbody are clamped to- O C represent two plates which are secured to end plate a by means of the screws 5 0. Plate O is cup-shaped to enable it to extend over the bearing B, and thus to economize space. llampediirmlybetween platesO and C is the cylindrical resistance R, which is made up of three sections, as designated by the 7 letters 9*, "1' and 0- each of which is composed of an edgewise-wound strip of resistance material. These sections are separated by the two conducting-rings I and J, which are in electrical contact with the adjacent turns of the re- 7 5 sistance B. This construction enables excellent electrical contact to be obtained between the resistance-sections and theleads therefrom. The rings I and J are connected to the rotorcoils a by means of leads, one of which, 7", is 0 shown in Fig. 2. The rings I and J are each provided with portions Z and j, which are bent into a direction parallel with the shaft. These portions form the stationary switch-contacts. The movable contact H is carried by a ccntrif- 8 5 ugal member D, pivoted on plate O at (Z, as shown in Fig. l, and normally pressed against the adjustable stop F by means of the leafspring G, one end of which is clamped to the stationary support 0 and the other end of 9 which engages the pivoted member D. By means of the adjustable stop F the speed at which the pivoted member D operates may be adjusted as desired. It will be seen by the arrangement of the member D and spring 9 5 G that the tension of spring Or is very little increased when the member D is moved to bring contact H into engagement with stationary contacts 2' and y'. Therefore member D is enabled to bear with strong pressure on the contacts when moved outward by centrifugal force, insuring a good electrical connection.

The circuit arrangement is as shown in Fig. 3. p represents the primary winding of the motor, which I have shown as three-phase, connected to the three-phase line L. a represents the secondary winding which I have shown as three-phase Y-connected, two terminals of which are connected to the conducting-rings I and J through the leads a" and The rings I and J are in electrical connection with the junction of resistances 7", 1 and r respectively, as has been heretofore explained. The outer ends of resistances r and 9' are both grounded on the end plates of the motor, as is indicated by the earth connection in Fig. 3. The member D, which is in electrical connection with the movable contact H, is also grounded, as shown, as is also the third terminal of the secondary winding (0. With the member D in the position shown it will be seen that the resistances 0 1' and 0' are connected in delta to the terminals of the secondary winding a. The motor secondary starts with the resistance properly connected in series with the secondary member. As the motor speeds up and member D is moved outwardly by centrifugal force to bring contact H into engagement with contacts and it will be seen that the secondary member is directly short-circuited and the motor operates with a short-circuit secondary.

With the construction as heretofore described it will be seen that a compact arrangement is secured, that the movable contacts are completely inclosed by the resistance and the plates C C, soas to remove all danger of fire from arcing, and that owing to the arrangement of the resistance no insulation whatever is required between the resistance and its support or between the movable member and the frame. Excellent electrical contact is secured between the resistance terminals and the resistance leads and contacts by means of the flat conducting-plates, and by reason of the arrangement of the centrifugal switch a proper contact is obtained when the switch is in its closed position.

Although in the diagram of connections I have shown a three-phase motor, it will be understood that my invention is not limited to this specific number.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. In a starting-switch for electric motors, a resistance having its extremities grounded on the motor-frame and leads connected to one or more intermediate points on said resistance.

2. In a starting-switch for electric motors, a resistance having its extremities grounded on the motor-frame and having leads connected to two intermediate points so as to form a delta-connected resistance with one point of the delta grounded.

3. In a starting-switch for electric motors, a cylindrical resistance clamped between supporting-plates and in electrical contact therewith, and one or more leads connected to intermediate points on said resistance.

4. In a starting-switch for electric motors, a cylindrical resistance formed of edgewisewound conducting-strips, supporting-plates clamped against the ends of said resistance and in electrical contact therewith, and one or more flat conducting-plates inserted at intermediate points in said resistance and adapted to serve as terminals therefor.

5. In a starting-switch for electric motors, a centrifugally-operated switch member, and a resistance and supporting-plates therefor surrounding and inclosing said member.

6. In a starting-switch for electric motors, a centrifugallyoperated switch member, a cylindrical resistance surrounding saidmember, and supporting-plates for said resistance serving with said resistance to inclose said member.

7 In a starting-switch for electric motors, a centrifugally-operated switch member, a cylindrical resistance surrounding said member, and conducting-plates inserted at intermediate points in said resistance and having bent portions adapted to be engaged by said member.

8. In a starting-switch for electric motors, a centrifugally-operated switch member, a cylindrical resistance surrounding said member and composed of sections of edgewisewound resistance-strips, and flat conductingplates inserted between adjacent sections and in electrical contact therewith and having bent portions adapted to be engaged by said member.

9. In a starting-switch for electric motors, a starting resistance, and a centrifugally-operated switch member adapted to short-circuit said resistance, said member and the extremi ties of said resistance being connected to a point on the rotor-winding of the motor through grounds on the motor-frame.

10. In a starting-switch for electric motors, a resistance connected at points intermediate of its extremities to points on the rotor-winding of the motor, and a centrifugally-operated switch member adapted to short-circuit said intermediate points on the resistance, said member and the extremities of said resistance being connected to a point on said rotor-winding through grounds on the motor-frame.

11. In combination with an electric motor, a starting resistance therefor carried at one end of the revolving member thereof and arranged to extend outwardly over the bearing at that end.

12. In combination with an electric motor, astarting resistance therefor, and supporting- ITO plates for said resistance secured to one end of the rotor, the outer plate being cup-shaped so as to extend outwardly over the hearing at that end of the rotor.

13. In combination With an electric motor, a cylindrical starting resistance carried at one end of the rotor and extendingoutwardly over the bearing.

14. In a starting-switch for electric motors, a pivoted centrifugally-operated switch memher, and a leaf-spring engaging said member at a point near its pivot.

15. In a starting-switch for electric motors,

a pivoted centrifugally-operated switch memher, and a restraining-Mining therefor engaging said member at a point near its pivot so that a slight movement only of said spring is produced by the movement of said member to its closed position.

In witness whereof I have hereunto set my hand this Qth day of May, 1904:.

JOHN B. WVIARD.

WVitnesses:

DUGALD MoK. MoKILLor, JOHN A. MoMANUs. 

